The 'ping' command

The 'ping' command is used to check if another site is active. All sites connected to the internet are required to be able to return a signal if a particular signal is sent to them. The sent signal is called a ping. The originating site sends a series of 'pings' at the target site and the target site then sends similar ones back. The ping program then uses the times between the sent pings and the returned ones to work out how slow the connection is and the number of non-returned pings to work out how reliable it is. The output will look something like this:

skynet:~> ping itd1.ul.ie
PING itd1.ul.ie (136.201.1.1): 56 data bytes
64 bytes from 136.201.1.1: icmp_seq=0 ttl=255 time=11.7 ms
64 bytes from 136.201.1.1: icmp_seq=5 ttl=255 time=5.5 ms
64 bytes from 136.201.1.1: icmp_seq=6 ttl=255 time=6.0 ms
64 bytes from 136.201.1.1: icmp_seq=7 ttl=255 time=5.5 ms
64 bytes from 136.201.1.1: icmp_seq=8 ttl=255 time=6.1 ms
ò
--- itd1.ul.ie ping statistics ---
5 packets transmitted, 5 packets received, 0% packet loss
round-trip min/avg/max = 5.5/6.4/11.7 ms